WASHINGTON (Bloomberg) -- Auto and technology companies are battling over a slice of coveted radio waves, with carmakers arguing the potential for lifesaving crash-avoidance systems should take precedence over more Wi-Fi for Web data and video.

U.S. Transportation Secretary Anthony Foxx said Feb. 3 his department will write rules for talking cars before President Barack Obama leaves office. That set up a tussle between the two sides, led by General Motors Co. and Comcast Corp., which among them spent almost $200 million last year to influence lawmakers and regulators in Washington.

Automakers said they're getting close to deploying technology Foxx described as a "moon shot" that could save as many lives as seat belts. Comcast, Google Inc. and Microsoft Corp., calling the systems more of a long shot, are pushing the Federal Communications Commission to let them at least share spectrum reserved for automakers 15 years ago.

"If we can't show we're utilizing it effectively, then we're going to lose the battle," said Scott Belcher, CEO of the Intelligent Transportation Society of America, a Washington coalition that advocates for technology in surface transportation.

The competition will force regulators to balance the desire to reduce the 30,000 deaths that occur on U.S. highways each year against the needs of data-hungry businesses and consumers, as the shrinking amount of open spectrum leaves little room for new uses that don't bump against others.

Technology companies say they can share airwaves without interfering with the safety systems. Auto interests are wary.

Wi-Fi congestion

Google, Microsoft and Comcast joined Feb. 13 in announcing a new advocacy group, WiFiForward, to push for expanded access to airwaves.

Three days earlier, FCC aides, including an adviser to agency Chairman Tom Wheeler, met about expanding Wi-Fi with representatives of Google, Microsoft, and the National Cable & Telecommunications Association, whose members include the nation's two largest cable TV companies, Comcast and Time Warner Cable Inc. Comcast last week proposed buying Time Warner for about $45.2 billion in stock.

Automakers say they've spent tens of millions of dollars developing technology, using their airwaves, that will let cars talk with each other and with highway sensors at short range.

They'll be able to let drivers know when two vehicles are approaching an intersection simultaneously or about to collide in adjacent lanes, or if they're approaching a vehicle ahead too quickly.

The systems could be installed in new cars, at a cost of about $100 a vehicle, or sold as aftermarket devices.

'Functionally unused'

Technology companies and cable providers want to expand Wi-Fi capacity to help handle mobile data traffic that grew 81 percent globally in 2013 as network connection speeds more than doubled, according to a report from Cisco Systems Inc., the world's biggest maker of network routers and switches. More than half the traffic was video, according to the report.

The FCC is considering a proposal to allow sharing of the automakers' airwaves made last year by former Chairman Julius Genachowski. He called Wi-Fi congestion a problem at airports, other public venues, and in homes.

Comcast last year told the FCC that the talking-car airwaves are "functionally unused" by the automakers, with commercial deployment possibly decades away.

Genachowski's successor, Wheeler, in December told Congress he supports more airwaves use, and said the FCC needs to study questions about sharing the auto airwaves. At a November hearing Julius Knapp, the agency's chief technology officer, told lawmakers "a considerable amount of work remains to be done."

Mark Wigfield, an agency spokesman, declined to comment.

'Toughest piece'

The auto frequencies are "maybe the single toughest piece" of proposals to allow Wi-Fi in more airwaves, said Michael Calabrese, director of the Wireless Future Project at the Washington-based policy group New America Foundation, who represented consumers at the Feb. 10 meeting with FCC aides.

"The auto industry, like every other incumbent, is trying to hold onto all the spectrum it can because it's valuable, and they want to keep all their options open," Calabrese said in an interview.

Computer and Internet companies spent $140.1 million on lobbying last year, led by Google and Microsoft, according to the nonpartisan Center for Responsive Politics in Washington.

No slouch itself, the auto industry spent $58.2 million on lobbying in 2013. The industry's top two corporate spenders are GM and the Alliance of Automobile Manufacturers.

GM spent $8.8 million last year on lobbying, both for its own in-house team and for the services of 10 outside firms. The alliance, meanwhile, spent $6.5 million for activities of its own trade-group lobbyists and seven other K Street firms.

Deadly interference

Cars with crash-avoidance technology will depend on multiple simultaneous transmissions from sensors to scan in all directions. Even momentary interference with one of those could result in a crash that could have been prevented, said Mike Stanton, president and CEO of the Washington-based Association of Global Automakers.

"There needs to be more analysis before anybody gets into that spectrum," said Michael Robinson, GM's vice president of sustainability and global regulatory affairs. "A lot more research has to be done to assure us all we're not going to have interference. We don't what to jeopardize that."

The National Highway Traffic Safety Administration estimates that as much as 80 percent of the almost 5 million crashes on U.S. highways could be prevented through the widespread use of talking-car communications. U.S. highway deaths increased in 2012 for the first time since 2005, with 33,561 people killed.

One quarter

"It's a huge advance in safety, one that cannot be overstated," Foxx said.

Wi-Fi providers agree they shouldn't interfere with auto systems, Mary Brown, Cisco's Washington-based director of technology and spectrum policy, said in an interview. The San Jose, Calif., gear maker favors sharing the airwaves.

"We just want access to spectrum when they're not using it," Brown said.

The auto industry may need only about one-quarter of its allotted airwaves because they operate on narrow frequencies, Calabrese said. "They could be sharing that band with other uses," he said.

Qualcomm Inc., the largest maker of the mobile-phone chips, has proposed reserving almost half the contested airwaves for auto-safety functions, and having more discussions for sharing in the remainder.

"I hope we're not in danger of a stalemate," Dean Brenner, a senior vice president for government affairs at the San Diego company, said in an interview. Qualcomm supplies auto markets and Wi-Fi, and wants both to prosper, he said.